THE MERIDIONAL CIRCULATION IN THE SOUTHERN-OCEAN AND ITS SEASONAL VARIABILITY AS SEEN BY THE FINE-RESOLUTION ANTARCTIC MODEL

A fine-resolution primitive equation model is used to investigate the seasonal variability of the interocean mass exchange via the Southern Ocean. The meridional overturning is calculated on both depth levels a nd density layers. The interocean mass exchange is estimated from the meridional stream functions in the different oceans. The annual averag e is found to be mainly governed by the thermohaline circulation in th e so-called oceanic conveyor belt, The seasonal variability is mainly due to changes in the wind stress, which are not necessarily local. Th e largest seasonal variability is found in the Pacific Ocean around 30 degrees S and around 34 degrees S in the Indo-Atlantic. In the Indo-A tlantic there are two meridional cells merged into each other at the s urface but driven by the northward Ekman transport at two different la titudes. The deepest one, which is part of the conveyor belt, has a se asonal variability driven by the changes in the northward Ekman transp ort at 35 degrees S. The shallower one (Deacon Cell) is driven further south at 43 degrees S, where the zonal wind stress reaches its maximu m. Simple relationships with the meridional Ekman transport, the merid ional thermohaline transport, and the total interocean exchange of wat er masses are found among the three world oceans. The meridional strea m function, simulated by an analytical model, shows that seasonal vari ability of the fine-resolution Antarctic model is barotropic and its b aroclinic circulation is mainly stationary.